Many clinical factors predict the aggressive course of CD. Younger age at initial diagnosis, the presence of perianal lesions, ileal involvement, smoking, and the need for therapy with corticosteroids are the major predictors of disabling disease or change of behavior to a more aggressive disease. On the other hand, treatment with azathioprine and biologic agents and colonic localization of disease are the major factors that are predictive of less aggressive CD course. The problem we face with determining the factors that increase the risk of disabling disease is that there is no standardized and consistent definition of disabling or aggressive disease. Only two studies analyzed predictors using the same definition of aggressive disease. Only Beaugerie and colleagues developed the score predictive of disabling disease based on three independent factors associated with disabling course that were present at the time of initial diagnosis of CD (requirement of corticosteroids, age less than 40 years, and presence of perianal disease). This score ranged from 0 to 3 points based on the presence of given parameters. The positive predictive value was 0.91 and 0.93 in patients having two or three risk factors, 0.61 for no factors present, and 0.67 for one factor present. In order to determine factors predictive of disabling CD there is a need to establish consistent definition of disabling disease with subsequent future studies on large group of patients to validate such definition and determine factors that may predict the aggressive course.